The dissension among Republicans over immigration that flared anew this week, sparking talk of an open revolt against House Speaker John A. Boehner, gave Democrats a rhetorical opening that Nancy Pelosi and others were more than happy to fill Thursday. Speaking to reporters at her weekly press conference, the House minority leader said she believes Boehner supports action on immigration, but is hamstrung by hard-liners in the GOP. “He ran it up the flagpole. We saluted, his caucus cut the flagpole down,” she said.